- * context to work on. as an approximation to fixing this,
- * let's encapsulate only the layers which don't have the
- * full plane as their bounding rect. that tends to catch
- * the layers we want to catch, but still isn't quite right
- * (consider the circle layer with 'invert' enabled, for
- * instance)
+ * context to work on. the Layer::reads_context() method
+ * returns true for layers which need to be able to see
+ * their context. we can't encapsulate those.